# SPDX-License-Identifier: AGPL-3.0-only
# Copyright 2026-present the Unsloth AI Inc. team. All rights reserved. See /studio/LICENSE.AGPL-3.0

"""Ollama model inventory: manifest parsing and writable-symlink materialization.

Ollama stores models content-addressed under ``<root>/manifests/`` and
``<root>/blobs/``. Inventory scans read the manifests directly (no writes),
returning rows whose ``id`` is an opaque ``ollama-manifest:`` reference. The
load path then calls :func:`materialize_ollama_model_ref`, which creates a
``.gguf``-named symlink (or hardlink) so that downstream loaders see a path
with the GGUF suffix without copying multi-GB blobs inside an API request.
"""

from __future__ import annotations

import hashlib
import json
import os
import uuid
from pathlib import Path
from typing import List, Optional
from urllib.parse import quote, unquote

from loggers import get_logger

from hub.schemas.inventory import LocalModelInfo
from hub.services.models.common import (
    _capabilities_for_format,
    _local_inventory_id,
)
from hub.utils.paths import (
    cache_root,
    ollama_model_dirs,
    path_is_same_or_child,
    tmp_root,
)

logger = get_logger(__name__)

_OLLAMA_MANIFEST_REF_PREFIX = "ollama-manifest:"
_OLLAMA_BLOB_NAME_CHARS = frozenset(
    "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789._+-"
)


def _ollama_manifest_ref(tag_file: Path) -> str:
    return f"{_OLLAMA_MANIFEST_REF_PREFIX}{quote(str(tag_file), safe = '')}"


def _safe_is_file(path: Path) -> bool:
    try:
        return path.is_file()
    except OSError:
        return False


def _ollama_blob_path(blobs_dir: Path, digest: object) -> Optional[Path]:
    if not isinstance(digest, str):
        return None
    algorithm, separator, value = digest.partition(":")
    if separator != ":" or not algorithm or not value:
        return None
    name = f"{algorithm}-{value}"
    if (
        not name
        or name in (".", "..")
        or any(char not in _OLLAMA_BLOB_NAME_CHARS for char in name)
        or not name.isprintable()
    ):
        return None
    return blobs_dir / name


def _contained_link_path(link_dir: Path, link_name: str) -> Optional[Path]:
    """Resolve *link_name* to a direct child of *link_dir*, or ``None``. ``link_name`` derives from manifest fields, so requiring a direct child keeps a crafted value with separators, ``..``, or a drive prefix from escaping the links dir."""
    if not link_name or link_name in (".", ".."):
        return None
    link_path = link_dir / link_name
    try:
        if link_path.parent.resolve() != link_dir.resolve():
            return None
    except OSError:
        return None
    return link_path


def _ollama_links_dir(ollama_dir: Path) -> Optional[Path]:
    """Writable directory for Ollama ``.gguf`` symlinks. Prefers ``<ollama_dir>/.studio_links/`` next to the blobs; falls back to Studio's cache (read-only system installs), then the temp dir (sandboxed installs)."""

    def _ensure_writable_dir(path: Path) -> Optional[Path]:
        try:
            path.mkdir(parents = True, exist_ok = True)
            probe = path / f".write-test-{uuid.uuid4().hex[:8]}"
            probe.mkdir()
            probe.rmdir()
            return path
        except OSError as e:
            logger.debug("Ollama link dir %s is not writable: %s", path, e)
            return None

    primary = ollama_dir / ".studio_links"
    if _ensure_writable_dir(primary) is not None:
        return primary

    # Namespace by a hash of the ollama_dir so two different Ollama roots
    # don't collide. This is a cache path, not a security boundary.
    try:
        digest = hashlib.sha256(str(ollama_dir.resolve()).encode()).hexdigest()[:12]
    except (OSError, RuntimeError):
        digest = "default"

    fallback = cache_root() / "ollama_links" / digest
    if _ensure_writable_dir(fallback) is not None:
        return fallback

    tmp_fallback = tmp_root() / "ollama_links" / digest
    if _ensure_writable_dir(tmp_fallback) is not None:
        return tmp_fallback

    logger.warning(
        "Could not create a writable Ollama link directory for %s",
        ollama_dir,
    )
    return None


def _make_ollama_blob_link(link_dir: Path, link_name: str, target: Path) -> Optional[str]:
    """Create a .gguf-named link to an Ollama blob: tries symlink then hardlink, skips the model if neither works (a full multi-GB copy would block the API). Idempotent."""
    try:
        link_dir.mkdir(parents = True, exist_ok = True)
    except OSError as e:
        logger.warning(
            "Could not create Ollama link directory %s: %s",
            link_dir,
            e,
        )
        return None
    link_path = _contained_link_path(link_dir, link_name)
    if link_path is None:
        logger.warning("Refusing unsafe Ollama link name %r under %s", link_name, link_dir)
        return None
    try:
        resolved = target.resolve()
    except OSError as e:
        logger.debug("Could not resolve Ollama blob %s: %s", target, e)
        return None

    # Skip if the link already points at the same blob. Use samefile, not size:
    # `ollama pull` can swap a tag to a same-sized blob, leaving a stale link.
    try:
        if link_path.exists() and os.path.samefile(str(link_path), str(resolved)):
            return str(link_path)
    except OSError as e:
        logger.debug("Error checking existing link %s: %s", link_path, e)

    tmp_path = link_dir / f".{link_name}.tmp-{uuid.uuid4().hex[:8]}"
    try:
        if tmp_path.is_symlink() or tmp_path.exists():
            tmp_path.unlink()
        try:
            tmp_path.symlink_to(resolved)
        except OSError:
            try:
                os.link(str(resolved), str(tmp_path))
            except OSError:
                logger.warning(
                    "Could not create link for Ollama blob %s "
                    "(symlinks and hardlinks both failed). "
                    "Skipping model to avoid blocking the API.",
                    target,
                )
                return None
        os.replace(str(tmp_path), str(link_path))
        return str(link_path)
    except OSError as e:
        logger.debug("Could not create Ollama link %s: %s", link_path, e)
        try:
            if tmp_path.is_symlink() or tmp_path.exists():
                tmp_path.unlink()
        except OSError as cleanup_err:
            logger.debug("Could not clean up tmp path %s: %s", tmp_path, cleanup_err)
        return None


def _ollama_model_info_from_manifest(
    ollama_dir: Path,
    tag_file: Path,
    *,
    materialize_links: bool = False,
    links_root: Optional[Path] = None,
) -> Optional[LocalModelInfo]:
    manifests_root = ollama_dir / "manifests"
    blobs_dir = ollama_dir / "blobs"

    try:
        rel = tag_file.relative_to(manifests_root)
    except ValueError:
        return None
    parts = rel.parts
    if len(parts) < 3:
        return None

    host = parts[0]
    repo_parts = list(parts[1:-1])
    tag = parts[-1]

    if host == "registry.ollama.ai" and repo_parts and repo_parts[0] == "library":
        repo_name = "/".join(repo_parts[1:])
    elif host == "registry.ollama.ai":
        repo_name = "/".join(repo_parts)
    else:
        repo_name = "/".join([host] + repo_parts)

    if not repo_name:
        return None

    try:
        manifest = json.loads(tag_file.read_text())
    except (json.JSONDecodeError, OSError) as e:
        logger.debug("Skipping unreadable/invalid Ollama manifest %s: %s", tag_file, e)
        return None

    config = manifest.get("config", {})
    config_digest = config.get("digest", "") if isinstance(config, dict) else ""
    model_type = ""
    file_type = ""
    if config_digest and blobs_dir.is_dir():
        config_blob = _ollama_blob_path(blobs_dir, config_digest)
        if config_blob is not None and _safe_is_file(config_blob):
            try:
                cfg = json.loads(config_blob.read_text())
                model_type = cfg.get("model_type", "")
                file_type = cfg.get("file_type", "")
            except (json.JSONDecodeError, OSError) as e:
                logger.debug("Could not parse Ollama config blob %s: %s", config_blob, e)

    layers = manifest.get("layers") or []
    if not isinstance(layers, list):
        return None

    model_blob: Optional[Path] = None
    gguf_link_path: Optional[str] = None
    stem_hash = hashlib.sha256(rel.as_posix().encode()).hexdigest()[:10]
    model_link_dir = links_root / stem_hash if links_root is not None else None
    safe_name = repo_name.replace("/", "-")
    quant = f"-{file_type}" if file_type else ""

    for layer in layers:
        if not isinstance(layer, dict):
            continue
        media = layer.get("mediaType", "")
        digest = layer.get("digest", "")
        if not digest:
            continue

        if media == "application/vnd.ollama.image.model":
            candidate = _ollama_blob_path(blobs_dir, digest)
            if candidate is None or not _safe_is_file(candidate):
                continue
            model_blob = candidate
            if materialize_links and model_link_dir is not None:
                link_name = f"{safe_name}-{tag}{quant}.gguf"
                gguf_link_path = _make_ollama_blob_link(model_link_dir, link_name, candidate)

        elif materialize_links and media == "application/vnd.ollama.image.projector":
            candidate = _ollama_blob_path(blobs_dir, digest)
            if candidate is not None and _safe_is_file(candidate) and model_link_dir is not None:
                mmproj_name = f"{safe_name}-{tag}-mmproj.gguf"
                _make_ollama_blob_link(model_link_dir, mmproj_name, candidate)

    if model_blob is None:
        return None
    if materialize_links and not gguf_link_path:
        return None

    suffix = ""
    if model_type:
        suffix += f" ({model_type}"
        if file_type:
            suffix += f" {file_type}"
        suffix += ")"

    try:
        updated_at = tag_file.stat().st_mtime
    except OSError:
        updated_at = None

    display = f"{repo_name}:{tag}"
    model_id = f"ollama/{repo_name}:{tag}"
    path = gguf_link_path if materialize_links and gguf_link_path else str(model_blob)
    load_id = path if materialize_links else _ollama_manifest_ref(tag_file)
    return LocalModelInfo(
        id = load_id,
        inventory_id = _local_inventory_id("ollama", "gguf", model_id),
        load_id = load_id,
        model_id = model_id,
        display_name = display + suffix,
        path = path,
        source = "ollama",
        updated_at = updated_at,
        model_format = "gguf",
        runtime = "llama_cpp",
        capabilities = _capabilities_for_format("gguf", "ollama"),
    )


def scan_ollama_dir(
    ollama_dir: Path,
    *,
    limit: Optional[int] = None,
    materialize_links: bool = False,
) -> List[LocalModelInfo]:
    """Scan an Ollama models directory for downloaded models.

    Ollama uses a content-addressable layout
    (``manifests/<host>/<namespace>/<model>/<tag>`` + ``blobs/sha256-...``),
    iterated via ``rglob`` to find every depth. Each manifest's ``model`` layer
    holds the GGUF weights (vision models add a projector layer).

    Scans are read-only by default and return an opaque manifest reference;
    the load route later calls :func:`materialize_ollama_model_ref` to create a
    ``.gguf`` symlink/hardlink, keeping GET /local free of filesystem writes.
    """
    manifests_root = ollama_dir / "manifests"
    if not manifests_root.is_dir():
        return []

    found: List[LocalModelInfo] = []
    links_root = _ollama_links_dir(ollama_dir) if materialize_links else None
    if materialize_links and links_root is None:
        logger.warning(
            "Skipping Ollama scan for %s: no writable location for .gguf links",
            ollama_dir,
        )
        return []

    try:
        for tag_file in manifests_root.rglob("*"):
            if not _safe_is_file(tag_file):
                continue

            info = _ollama_model_info_from_manifest(
                ollama_dir,
                tag_file,
                materialize_links = materialize_links,
                links_root = links_root,
            )
            if info is None:
                continue
            found.append(info)
            if limit is not None and len(found) >= limit:
                return found
    except OSError as e:
        logger.warning("Error scanning Ollama directory %s: %s", ollama_dir, e)
    return found


def _ollama_dir_for_manifest(tag_file: Path) -> Optional[Path]:
    """Discovered Ollama root whose ``manifests/`` contains *tag_file*, or ``None``. Validating against known roots keeps a crafted reference from driving materialization to an arbitrary path."""
    for ollama_dir in ollama_model_dirs():
        if path_is_same_or_child(tag_file, ollama_dir / "manifests"):
            return ollama_dir
    return None


def materialize_ollama_model_ref(ref: str) -> str:
    """Resolve an ``ollama-manifest:`` reference to a loadable ``.gguf`` path,
    creating the writable symlink/hardlink on demand.

    Raises ``ValueError`` if the reference is malformed, points outside a
    discovered Ollama models directory, or cannot be materialized.
    """
    if not ref.startswith(_OLLAMA_MANIFEST_REF_PREFIX):
        raise ValueError("Not an Ollama manifest reference")

    tag_file = Path(unquote(ref[len(_OLLAMA_MANIFEST_REF_PREFIX) :]))

    ollama_dir = _ollama_dir_for_manifest(tag_file)
    if ollama_dir is None:
        raise ValueError("Reference is outside any known Ollama models directory")

    links_root = _ollama_links_dir(ollama_dir)
    if links_root is None:
        raise ValueError("No writable location for Ollama .gguf links")

    info = _ollama_model_info_from_manifest(
        ollama_dir,
        tag_file,
        materialize_links = True,
        links_root = links_root,
    )
    if info is None or not info.path:
        raise ValueError("Could not materialize Ollama model from manifest")
    return info.path
